The overhead per contact is 188 chars, this is quite a lot, we may select an alternate format later. `1,:{"action":,"aor":"","ruid":"","c":"","received":"","path":"","callid":"","user_agent":"","instance":"","expires":,"cseq":,"flags":,"cflags":,"q":,"last_modified":,"methods":,"reg_id":},`
I think we could validate the size of the packet while building it to automatically send > 60000 for example.